Effective waste water treatment is a major concern of the industrialized world. Waste water often contains phosphorous and nitrogen which stimulates unwanted algae growth, creating unpleasant tastes and odors in the water supply; and operating problems in wastewater treatment plant. Wastewater treatment can be accomplished by physical/chemical methods or biological methods. Biological nitrification is a common biological method for removal of ammonia nitrogen in wastewater. The microorganisms involved are the nitrifying bacteria, nitrosomonas, and nitrobacter. Nitrification is the biological oxidation of ammonia nitrogen to nitrate nitrogen with nitrite nitrogen formation as an intermediate. This biological oxidation reaction produces the energy these bacteria need to assimilate inorganic carbon (IC), which is their sole carbon source for cell synthesis. See, Eckenfelder, Industrial Water Pollution Control, 2nd Edit. Nitrifying bacteria are sensitive to pH, temperature, heavy metals, and a number of organic and inorganic compounds. Other factors affecting nitrification performance are the amounts of dissolved oxygen (DO) and inorganic carbon (IC) in the bioreactor. Thus, the biological nitrification process can be easily upset. Traditionally, nitrifier populations are sensitive to minor operational upsets which require days to recover. This is a problem for waste water treatment facilities and usually results in an environmental excursion.
However, despite this sensitivity, the biological nitrification process remains a highly useful means for removing ammonia nitrogen in the art of wastewater treatment technology. Thus, due to the fact that nitrifying bacteria populations are easily upset, there is a need in the art for a method to quickly and accurately determine nitrifier populations. Currently, determination of nitrifier populations in an activated sludge process has been limited to estimating the concentrations based on mixed liquor concentrations and plate counts which requires seven days to complete. See, Wilson, G. S. and Miles, A. S. "Tropley and Wilson's Principles of Bacteriology and Immunity", The Williams and Wilkins Company, Baltimore, Md., 1964, pp2253-2563. Other references describing methods of determining nitrifier populations include, Carpenter, P. L., "Microbiology", W. G. Sanders Company, Philadelphia, Pa., 1961, pp 44-45 and Stanier, R. Y., Doudoroff, M. and Adelberg, E. A.; "The Microbial World", 3rd edition, Prentice Hall, Inc., New Jersey, 1970, pp 78-96; Downing, A. L., "Advances in Water Quality Improvement", Vol. 1, University of Texas Press, Austin, Tex. and Eckendelder, Wesley W., Jr., "Industrial Water Pollution Control", McGraw-Hill Book Company, 1989, pp 173-176; Metcalf and Eddy, Inc., "Wastewater Engineering: Treatment/Disposal/Reuse", 2nd edition, McGraw-Hill Book Company, 1979, pp 398-408, and Eckenfelder, Wesley W., Jr., "Principles of Water Quality Management", CBI Publishing Company, Inc., Boston, Mass., pp 317-325. The current methods are problematic, since there is no analytical basis for estimation of nitrifier populations.
Applicants' have solved the aforementioned problem in the art. Specifically, Applicants have developed the Nitrification Activity Test (NAT) to support daily wastewater treatment plant operational control with a test procedure that more accurately evaluates the nitrifier performance within a reasonable time period. The Applicants' NAT differentiates heterotrophic and autotrophic respiration rates within a thirty minute period and accurately demonstrates a correlation of the nitrification activity when compared to ammonia nitrogen removal efficiencies. The test results from the NAT procedure can be used to evaluate and control nitrification sludge age requirements and nitrification inhibition effects due to pH, temperature, dissolved oxygen levels, and varying substrates. The NAT procedure can also be used to evaluate acute toxicity in the wastewater treatment facility. The Applicants' test procedure uses standard laboratory equipment and reagents.